MET1010 CHAPTER 6

Air Pressure

Force that is exerted onto every surface due to the collision of gas molecules

Barometer

Measures pressure in inches

Pressure gradient

-Directs air from High to Low pressure

-Due to heating difference.

When there is a greater difference in pressure, there is a

steep pressure gradient which leads to strong winds

When there is a smaller difference in pressure there is a

weak pressure gradient which leads to weaker winds

Coriolis effect

-Due to the Earth’s rotation

-Northern Hemisphere wind will deflect towards the right

-Southern Hemisphere winds will deflect towards the left

-Acts a right angle to wind and affects wind direction

Coriolis effect is affected by? and how?

-Wind speed: the faster the winds are moving, the greater the deflection and vice versa for slower winds.

-Latitude: the Coriolis effect is greater at the poles (north and south) and weakest at the equator

Centrifugal Force

-An outward pull in a curved flow that is a function of wind speed

Friction

-Acts the opposite of wind, ultimately slowing down its speed and direction

-Acts only at the surface , never upper levels

Gravity

-Downward and directed toward the center of the earth

Geostrophic wind

Balance between the pressure gradient force and Coriolis, so air moves parallel to isobars

In the southern hemisphere upper level wind moves

-Counter-clockwise and parallel to isobars for high pressure

-Clockwise and parallel to isobars for low pressure

In the northern hemisphere upper level wind moves

-Clockwise and parallel to isobars for high pressure

-Counterclockwise and parallel to isobars for low pressure

In the southern hemisphere surface level wind moves

-Counter-clockwise and crosses isobars outwardly for high pressure

-Clockwise and crosses isobars inwardly for low pressure

In the northern hemisphere surface level wind moves

-Clockwise and crosses isobars outwardly for high pressure

-Counter-clockwise and crosses isobars inwardly for low pressure

Cyclone

Area of low pressure

Anticyclone

Area of High pressure

If the air is rotating cyclonically then..

It is moving counterclockwise in the northern hemisphere and clockwise in the southern hemisphereI

If the air is moving anticyclonically then..

It is moving clockwise in the northern hemisphere and counterclockwise in the southern hemisphere

Wind vane

Points into the wind and measures the wind direction

Cup Anemometer

measures wind speed